For the tubed or barrelled artillery of the 20th century, extremely high rates of fire will be required, since the time between opening fire and up to the point in time when the opponent, after identifying and ranging of the firing gun, is ready to commence combatting this with his own artillery is becoming shorter and shorter. Within the brief space of time which is thus available from opening fire and up to the time when the firing piece must be moved to avoid being knocked out, a sufficient number of shells must, thus, have had time to be discharged in order to have sufficient effect on the target, which, for single targets, may be assumed to be between 3 and 10 rounds.
Since the primary consideration in this application is medium-caliber or large-caliber artillery pieces (in other words of a caliber from about 7.5 cm and larger), the weight of the shells will be relatively great and, at the same time there is a main weight difference between the shell and its propellant charge.
Automatically loading an artillery gun with cartridged ammunition presents no serious problem, since each cartridge is handled and rammed in the firing position of the gun as a rigid self-contained unit. Granted, the increasingly common, combustible cases nowadays employed in separate-loading ammunition impart to the propellant charges a markedly better stability than the older gun cotton propellant charges, but the combustible cases are nevertheless generally not so rigid that they can carry a shell, for which season the shell and the propellant charges must be rammed home separately without being fixedly connected to one another.
For high fixing sates, high ramming speeds are necessary. This, combined with the need for guiding both the shell and the propellant charge during the ramming operation, as well as the large weight difference between shell and propellant charge places particular requirements on how the ramming operation is executed.